High-pressure viscosity measurements of traction oils up to 2GPa at up to 200°C

High-pressure viscosity was measured for synthetic traction oils including a CVT oil up to 2 GPa at elevated temperature up to 200 degrees C employing a falling sphere method in a diamond-anvil pressure cell (DAC) with appropriate heating system. The obtained results almost showed the linearity between logarithmic viscosity and pressure at all temperature (40 degrees C similar to 200 degrees C) with some data scattering. The accuracy of this high pressure viscometry was confirmed with the existing data at low pressure. Viscosity-pressure coefficent a decreased to 1/3 similar to 1/4 at 200 degrees C of that at 40 degrees C. Simple experimental expression of temperature depending a was suggested referring to Eyring viscosity formula. Pressure temperature phase diagrams of liquid-solid transition were plotted from the obtained high pressure viscosity, which predict traction feature.